Currently, applications of thyristors in an alternating-current power grid to control electric capacitors, motors, and heating elements become more popular, where a thyristor driving apparatus for the thyristors is driven by transformers in an isolated manner or driven by high-voltage electronic switches, which has the following disadvantages:
1. Driven by a transformer in an isolated manner: A thyristor driving signal is provided by a transformer. A pulse signal generating circuit, a transformer driving circuit, the transformer, and a rectifier circuit are needed. There are disadvantages such as high-frequency pollution, a large occupied space, and a low cost-effectiveness.
2. Driven by a high-voltage electronic switch: A thyristor driving signal is sent from a main loop of a thyristor, via a resistor and a high-voltage electronic switch (for example, a high-voltage photoelectric coupler such as MOC3083), to a trigger electrode of the thyristor. The high-voltage electronic switch withstands a relatively high voltage, and a plurality of high-voltage electronic switched is needed for being connected in series for use in a 380V system, which has disadvantages of having poor reliability and being easy to breakdown.